1. Field of the Invention
This invention relates to a dielectric ceramic composition for high frequency wave having a specific dielectric constant xcex5r of 10 to 20, and less dielectric loss tan xcex4 in a high frequency wave region, and capable of easily controlling temperature coefficient xcfx84f at the resonant frequency (f0)
2. Description of the Related Art
With the rapid progress of communication networks in recent years, frequencies used for communication have been extended and reached high frequency wave regions such as microwave regions or milli-wave regions. The size of the microwave circuits or milli-wave circuits can be miniaturized as a specific dielectric constant xcex5r is larger. However, if the specific dielectric constant xcex5r is excessively large, the fabrication accuracy is lowered regarding the high frequency region higher than the microwave region. Therefore, materials having relatively small specific dielectric constant xcex5r are necessary.
As the dielectric ceramic composition of this type, for example, BaOxe2x80x94MgOxe2x80x94WO3 series materials (Japanese Patent Laid-Open No. 236708/1994) and Al2O3xe2x80x94TiO2xe2x80x94Ta2O5 series material (Japanese Patent Laid-Open 52760/1997) have been proposed. However, they are not yet sufficient regarding the characteristics as the high frequency wave use and, a dielectric ceramic composition having further excellent characteristics has been demanded. Furthermore, from the point of mass production, less scattering of the characteristic against firing temperature fluctuation is requested.
Meanwhile, alumina (Al2O3) exhibits satisfactory dielectric characteristics having a specific dielectric constant xcex5r of 9.8 and tan xcex4 of 3 to 5xc3x9710xe2x88x925 at a measuring frequency of 10 GHz but since the temperature coefficient xcfx84f at the resonance frequency (f0) is xe2x88x9255 ppm/xc2x0 C., the application use is restricted. Further, the firing temperature of Al2O3 is as high as 1600xc2x0 C. or higher to result in a problem that the cost for the firing step is increased.
This invention intends to eliminate the problems described above and provide a dielectric ceramic composition for high frequency wave having a specific dielectric constant xcex5r of 10 to 20 and dielectric loss less tan xcex4, which is less scattering, and the absolute value of a temperature coefficient xcfx84f at the resonance frequency (f0) of 30 ppm/xc2x0 C. or less, which can easily be controlled.
This invention relates to a dielectric ceramic composition for high frequency wave having a composition comprising, Al, Zr, Ti, Sn, and O as a basic component and represented by the compositional formula:
aAl2O3-bZrO2-cTiO2-dSnO2 
(in which 0.4068 less than a less than 0.9550, 0 less than b less than 0.1483, 0.0225 less than c less than 0.3263, 0.0203 less than d less than 0.1186, a+b+c+d=1).
This invention can provide a dielectric ceramic composition for high frequency wave having a specific dielectric constant xcex5r of 10 to 20 and less dielectric loss tan xcex4 in a high frequency wave region, which is less scattering against firing temperature fluctuation, and capable of easily controlling a temperature coefficient xcfx84f at the resonant frequency (f0).